In your previous mail you wrote:
I don't have any "UNKNOWN" R/H state.
=> this is not a state, this is the bottom semantical value,
i.e. the absence of a state.
I don't have problem with what to do when transition R->H or H->R
happens. The problem is how I detect this transition with certain
class of Neigbor advertisements, specifically those that omit target
link layer address. Do I process the R bit or not?
=> if there is a TLL and TLL is forbiden or if there is no TLL
and TLL is mandatory then the NA is not valid and the R bit must not
be processed. Else the NA is valid and the R bit must be processed.
I believe your problem is more with validity checking than with the R bit.
In RFC-2461, section 7.2.5, there is quite complex sentence (for
me)...
.....If the Override flag is clear and the
supplied link-layer address differs from that in the cache, then one
of two actions takes place: if the state of the entry is REACHABLE,
set it to STALE, but do not update the entry in any other way;
otherwise, the received advertisement should be ignored and MUST NOT
update the cache.
=> this is a invalidity (sp?) statement. You have the explicit term "ignore".
If the Override flag is set, both the Override
flag is clear and the supplied link-layer address is the same as that
in the cache, or no Target Link-layer address option was supplied,
======================================
the received advertisement MUST update the Neighbor Cache entry as
follows: ...
So, depending on how you bind the or in ", or no Target", you may
get different implementations.
=> this is about the TLL, in any case the NA is valid and the R bit
must be processed.
That is, if link layer is using addresses, ignore Neighbor
advertisements without TLL totally?
=> no, ignore them for the link-layer address of the neighbor,
NOT for the R bit.
Regards
[EMAIL PROTECTED]
PS: you can try to understand the logic of the whole stuff too,
this is a simple state automaton.
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